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    SubjectRe: Identifying network namespaces (was: Network namespace manipulation with file descriptors)
    On Wed, May 18, 2011 at 4:33 PM, David Lamparter <> wrote:
    > On Wed, May 18, 2011 at 04:03:03PM +0300, Alexey Dobriyan wrote:
    >> On Wed, May 18, 2011 at 3:43 PM, David Lamparter <> wrote:
    >> > -   processes cannot easily be cross referenced with each other
    >> >
    >> >  in the case of user space stuff running astray - like management
    >> >  software crashing, routing daemons screwing up, etc. - it becomes
    >> >  fairly difficult to shut down a network namespace (or even reaquire
    >> >  physical devices that have been reassigned)
    >> It shutdowns itself when last process using netns disappeares,
    >> so if you kill your routing daemons you should be fine.
    >> Physical netdevices are moved to init_net.
    > Now assume I'm running pptpd, which forks a new pppd for each
    > connection. Even if I kill pptpd, the pppd keeps running... now how do I
    > find the pppds that belong to that one namespace that I'm trying to
    > get rid of?

    That's a valid question.

    >> > So, considering this set of premises (feedback welcome) I looked for
    >> > some suitable means of identification. I discarded going for any process
    >> > identifiers since Eric's patches allow for network namespaces without
    >> > any process holding a reference, using bind mounts instead.
    >> If anything it should be netns->id, /proc/*/netns outputting id
    >> where id is not derived from kernel pointer.

    Actually it should be symlink
    /proc/net/netns -> 0 # for init_net
    /proc/net/netns -> u32 (> 0) # for the rest
    to extract information by 1 syscall, not 3
    where netns id is totally random, so userspace won't make assumptions.
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      Last update: 2011-05-18 16:15    [W:0.022 / U:1.304 seconds]
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